/*
 * Copyright 2022 emo Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.qhplus.emo.device

class CacheRunner<T, R>(private val action: (T) -> R?) {

    @Volatile
    private var value: R? = null

    fun get(param: T): R? {
        return value ?: synchronized(this) {
            value ?: action(param)?.also { value = it }
        }
    }
}
